pasar dias a meses

[charlyta]

Hola. Intentando la siguiente función para convertir fechas no puedo pasar el resultado de días a meses. Se os ocurre algo?

Código Javascript:

function recalcDateDiff()
{
 var myForm = document.form1;
 var firstDay = myForm.firstDay.options[myForm.firstDay.selectedIndex].value;
 var secondDay =
     myForm.secondDay.options[myForm.secondDay.selectedIndex].value;
 var firstMonth =
     myForm.firstMonth.options[myForm.firstMonth.selectedIndex].value;
 var secondMonth =
     myForm.secondMonth.options[myForm.secondMonth.selectedIndex].value;
 var firstYear =
     myForm.firstYear.options[myForm.firstYear.selectedIndex].value;
 var secondYear =
     myForm.secondYear.options[myForm.secondYear.selectedIndex].value;
 var firstDate = new Date(firstDay + " " + firstMonth + " " + firstYear);
 var secondDate = new Date(secondDay + " " + secondMonth + " " + secondYear);
var daysDiff = (secondDate.valueOf() - firstDate.valueOf());
 daysDiff = Math.floor(Math.abs((((daysDiff  / 1000) / 60) / 60) / 24));
 
 myForm.txtDays.value = daysDiff;
 return true;
}